Prevent large amounts of UDP probes being sent consecutively.

We cannot reset udp_ping_sent to zero when we receive a valid reply to
an UDP probe, because that would cause a new one to be sent immediately
in try_udp(). Instead, add a bit to node_status_t to keep track of whether we
have a UDP probe that's waiting for a reply.

Thanks to Ronny Nilsson for spotting the source of the problem.

diff --git a/src/net_packet.c b/src/net_packet.c
index 5a856429b4446dd47a2c05c17f43bbd9d273330e..31c66d3248126fb7a913a973ecf09873d538edd7 100644 (file)
--- a/src/net_packet.c
+++ b/src/net_packet.c
@@ -152,11 +152,12 @@ static void udp_probe_h(node_t *n, vpn_packet_t *packet, length_t len) {
                len = ntohs(len16);
        }
 
-       if(n->udp_ping_sent.tv_sec != 0) {  // a probe in flight
+       if(n->status.ping_sent) {  // a probe in flight
                gettimeofday(&now, NULL);
                struct timeval rtt;
                timersub(&now, &n->udp_ping_sent, &rtt);
                n->udp_ping_rtt = rtt.tv_sec * 1000000 + rtt.tv_usec;
+               n->status.ping_sent = false;
                logger(DEBUG_TRAFFIC, LOG_INFO, "Got type %d UDP probe reply %d from %s (%s) rtt=%d.%03d", DATA(packet)[0], len, n->name, n->hostname, n->udp_ping_rtt / 1000, n->udp_ping_rtt % 1000);
        } else {
                logger(DEBUG_TRAFFIC, LOG_INFO, "Got type %d UDP probe reply %d from %s (%s)", DATA(packet)[0], len, n->name, n->hostname);
@@ -175,8 +176,7 @@ static void udp_probe_h(node_t *n, vpn_packet_t *packet, length_t len) {
                reset_address_cache(n->address_cache, &n->address);
        }
 
-       // Reset the UDP ping timer. (no probe in flight)
-       n->udp_ping_sent.tv_sec = 0;
+       // Reset the UDP ping timer.
 
        if(udp_discovery) {
                timeout_del(&n->udp_ping_timeout);
@@ -1132,6 +1132,7 @@ static void try_udp(node_t *n) {
        if(ping_tx_elapsed.tv_sec >= interval) {
                gettimeofday(&now, NULL);
                n->udp_ping_sent = now; // a probe in flight
+               n->status.ping_sent = true;
                send_udp_probe_packet(n, MIN_PROBE_SIZE);
 
                if(localdiscovery && !n->status.udp_confirmed && n->prevedge) {

diff --git a/src/node.h b/src/node.h
index 3daffd4a2b0eb97b9cf011cfe86dce1a182bfc71..1b33789ee0583c3195742ddd7aa1c1ccfe596d40 100644 (file)
--- a/src/node.h
+++ b/src/node.h
@@ -41,7 +41,8 @@ typedef struct node_status_t {
        unsigned int udppacket: 1;              /* 1 if the most recently received packet was UDP */
        unsigned int validkey_in: 1;            /* 1 if we have sent a valid key to him */
        unsigned int has_address: 1;            /* 1 if we know an external address for this node */
-       unsigned int unused: 20;
+       unsigned int ping_sent: 1;              /* 1 if we sent a UDP probe but haven't received the reply yet */
+       unsigned int unused: 19;
 } node_status_t;
 
 typedef struct node_t {